The subject matter disclosed herein relates to knock sensors, and more specifically, to utilizing knock sensors mounted to large, multi-cylinder reciprocating devices (e.g., combustion engine, reciprocating compressors, etc.) in conjunction with standard quality control techniques to improve knock margin detection and control for adjusting the exhaust gas recirculation (EGR) rate for EGR engines.
Combustion engines typically combust a carbonaceous fuel, such as natural gas, gasoline, diesel, and the like, and use the corresponding expansion of high temperature and pressure gases to apply a force to certain components of the engine, e.g., piston disposed in a cylinder, to move the components over a distance. Each cylinder may include one or more valves that open and close correlative with combustion of the carbonaceous fuel. For example, an intake valve may direct an oxidizer such as air into the cylinder, which is then mixed with fuel and combusted. Combustion fluids, e.g., hot gases, may then be directed to exit the cylinder via an exhaust valve. Accordingly, the carbonaceous fuel is transformed into mechanical motion, useful in driving a load. For example, the load may be a generator that produces electric power. Exhaust emissions from the engine generally includes pollutants, such as nitrogen oxides (NOx), unburnt hydrocarbons (HC), and carbon monoxide (CO). Internal combustion engines, such as reciprocating engines, may include a variety of features to reduce these exhaust emissions. Unfortunately, some pollutant reduction techniques may cause a narrow timing range such that a cylinder in the combustion engine may experience misfire (i.e., low firing timing) or knock (i.e., high firing timing).